Piston spreader



March 12, 1935. Q JQHNSQN 1,993,997

PI S'ION SPREADER Filed July 21, 1934 hven'tov Chafles 'Edoh son 44 MATrorne. g

Patented Mar. 12, 1935 UNITED STATES.

PATENT OFFICE 5 Claims.

This invention relates to piston expanders or Spreaders.

Lightweight pistons, made from aluminum alloys, are used in veryconsiderable quantities in internal combustion engines in motorvehicles. Such pistons are subject to wear and the coefilcient ofexpansion of the metal used differs from the metal of the cast ironcylinder block so that irrespective of how perfect the piston may workin an engine when the engine and pistons are new, it very frequentlyoccurs that after a period of use the piston becomes loose in thecylinder to a greater extent than is desirable, resulting in piston slapfrom looseness of the lower end of the piston with respect to thecylinder. Also in 'many cases there is oil pumped and loss and waste oflubricating oil at the upper portion of the piston, particularly afterthe piston rings,

- which are around the upper end of the piston,

have become considerably worn.

The correction of the trouble at the upper end of the piston by theinstallation of new piston rings is well known. Such correction as tooil pumped and waste of lubricating oil does not aid in overcoming thetroubles due to wear at the lower end or skirt of the piston. In manycases it has been common to rebore the cylinders and replace the pistonswith oversize pistons to fit said larger rebored cylinders, and supplynew rings for such larger pistons. Or instead of reboring the cylindersin some cases the cylinder block has been entirely replaced. Either isvery expensive.

With my invention, by means of a very simple and practical expanderapplicable at the inner sides and near the lower end of the pistonskirt, the piston can be properly expanded or enlarged so as tocompensate for wear in the piston and cylinder walls. Then when aninternal combustion engine is to be reconditioned, the replacement ofthe piston rings and the addition of the piston expander of my inventionplaces the engine, insofar as cylinders and pistons are concerned, againin substantial perfect condition and at a relatively very low cost. rThe invention and a preferred structure embodying the same will beunderstood from reference to the following description, taken inconnection with the accompanying drawing, in which, 7

Fig. 1 is a vertical'section through a piston equipped with theexpanderor spreader of my invention.

Fig. 2 is a horizontal section through the piston showing the expanderof my invention in plan,

one part thereof being longitudinally sectioned for clearness ofdisclosure.

Fig. 3 is a fragmentary enlarged transverse section on the line 33 ofFig. 2, and

Fig. 4 is a fragmentary vertical section on the line 44 of Fig. 2. ,1

Like reference characters refer to like'pa'rts in the differentfiguresof the-drawingfl The piston 1, usually of an aluminum alloy, for theapplication of the expander of my inven- 1 tion is slotted at one sideas indicated at 2. Many pistons of the light weight, aluminum alloycharacter have this slot when manufactured. Others have a slot extendingnearly to the lower edges of the piston in which case it is necessarymerely to continue the slot to the lower edges of the piston. Inpreparing the piston for the installation of my invention a continuousshallow groove 3 is. made at the inner side and near the lower end ofthe piston as shown, that is, the groove is at the inside of thedepending skirt of the piston.

The expander or spreader of my invention includes four parts. Two ofthem are duplicates consisting each of a body 4 made of a length of rodpreferably hexagonal in cross section. At one end the rod is interiorlydrilled and threaded as indicated at 5. At the other end it is drilledinwardly for a short distance, there being left an integral cross web 6between the inner ends of the two holes which are drilled inwardly fromthe ends of the body member'4. This is fully shown in Fig. 2.

Another member of the structure is made up into substantially U-shapefrom a length of stiff 35 wire rod and consists of a cross portion '7having a curvature such that it substantially fits the curvature of thegroove 3 in the piston, and from each end of which legs 8 project. Theselegs 8 are threaded so as to enter the threaded openings 5 in the bodymembers 4 previously described. The two members 4 may be readilythreaded onto the ends of the legs 8 in the assembly of theconstruction.

The remaining member of the structure is formed of spring wire rodhaving a curved intercircumferentially moreor less as desired. Secmorethan three.

ond, they provide resiliency whereby expansion and contraction of thepiston may occur.

In practice preferably the piston, diametrically opposite the slot 2,and in the plane of the groove 3 will have a small opening 13 drilledtherethrough. The part 7 at its outer side is formed with a projectinglug 14 to enter such opening, thereby locating the expander in thepiston and holding it against movement.

It will be noted with reference to Fig. 3 that the connecting portionsbetween the spring members and 11 bear against flat sides of thehexagonal body members 4. This provides a substantial lock to hold suchmembers 4 against any tendency to move and either thread inwardly oroutwardly on the legs 8. But by applying a proper wrench to the members4 the spring material from which the member is made yields sufficientlythat the expander may be adjusted at both sides to properly and snuglyengage the groove 3 made in the piston.

With this construction the expander may be located within the pistonfreely, that is, with the members 4 threaded onto the legs 8 a sum--cient distance so as to bring the two opposing sides 7 and 9 of theexpander toward each other sufiiciently that the expander may be veryreadily and easily placed within the piston. Then by applying the wrenchto the members 4 and turning the same so as to screw the same outwardlyon the legs 8 the opposed bearing portions 7 and 9 are moved away fromeach other and press against the bottom of the groove 3, fit the samesnugly and expand the piston to the desired degree.

When the piston is equipped with the expander and the expander properlyadjusted the lower end or skirt portion of the piston thereupon isproperly enlarged to compensate for any wear which has taken place ineither the walls of the cylinder or on the outer sides of the pistonskirt. The member consisting of the parts 9, 10, 11 and 12 being-ofyielding spring material, if a portion of the length of the cylinder isworn greater than another portion this yielding spring member will yieldor expand as may be necessary to take care of such difierences indiameter of the cylinder.

The piston expander or spreader of my invention is economical to make,very quickly and easily installed and is particularly effective inservice. An internal combustion engine, so far as pistons and cylindersare concerned, is very quickly and economically reconditioned throughthe replacement of the worn piston rings with new rings and the additionof the expander of my invention to the lower end or skirt of the pistonas described. Or if the rings are not worn so as to need replacementwhen piston slap develops, the expander alone may be installed.

One very good feature of the present invention is that any particularsize of piston expander made in accordance with my invention isapplicable to quite a number of pistons having different diameters, sothat for substantially the sizes of pistons used in automotive enginesit will not be required to make more than a very few standard sizes ofpiston expanders, probably not The spring character-of the bearingportion 9 will permit it to conio'rmto grooves in pistons 'of differentdiameters within a limited range, while the adjustment. permitted by thethreaded connection of the body members 4 on the legs 8 allows foradaptation of the expander to several sizes of pistons within a rangebetween the largest and smallest in diameter of one-half inch or more,without affecting the beneficial results obtained.

The invention is defined in the appended claims and is to be consideredcomprehensive of all forms of structure coming within their scope.

I claim:

1. A piston expander comprising, two spaced apart body memberslongitudinally drilled and threaded at one end and having longitudinalopenings drilled therein at the other end, providing stops between theinner ends of said openings, a member of spring material having a curvedintermediate section and formed at each end into reversely bent springloops and terminating in end portions received within said secondmentioned longitudinal openings and engaging against said stop, and amember having a curved intermediate portion and threaded end portionsadjustably received within said threaded openings of the body members.

2. A construction containing the elements in combination defined inclaim 1, said body members each having a plurality of flat sides againstwhich said spring loops bear to yieldingly hold I the body membersagainst turning movement.

3. A piston expander comprising, a member of spring wire having a curvedintermediate portion with reversely bent spring loops at the ends ofsaid intermediate portion, said loops having terminal end portionsparallel to each other, two members each having longitudinal openingstherein into which said terminal portions of the first member areinserted to bear against the bottoms of said openings, and an additionalmember upon which both of said second mentioned members are adjustablymounted, whereby said additional member and spring member may beadjusted inwardly or. outwardly with respect to each other.

4. A piston expander comprising, two elongated body members ofpredeterminedcross section and' surface, each longitudinally drilled andthreaded inwardly at one end for a distance, and longitudinally drilledor cored at the other end, the longitudinal openings in each body memberterminating short of each other, a member having threaded terminal endportions onto which the body members are threaded, an additional memberof spring material having an intermediate curved portion and parallelend portions, said end portions being received in the second of saidlongitudinalopenings and seated at their ends against the bottoms ofsaid openings, and means on said last mentioned spr'ng member adapted toyieldingly engage the sur ace of each of the body members to yieldinglyhold the same against turning movement.

'5. A piston expander of the class described comprising, two spacedapart body members each having a threaded opening and a second opening,a substantially U-shaped member having a curved intermediate section andthreaded legs on which said body members are adjustably second openingsin the said body members, as and for the purposes described.

L CHARLES E. JOHNSON.

